LIBRO DE OBSEQUIO SORPRESA 1 BREAST CANCER

24
Histological Diagnosis of Implant-Associated Pathologies
. . Fig. 20 Combination of conventional and corrosion metallic particles. Macrophages containing a mixture
of Cr-Co-Mo microparticles observed as pale green globular aggregates of nanoparticles generated by tribocorrosion
and Cr-Co-Mo gray–black, needle-shaped to polygonal, sharp-edged, microparticles generated
by edge loading in a case of metal-on-metal hip resurfacing arthroplasty (H&E, ×400)
are of nano-size ranging from less than 10 nm to 100 nm [48], [52], and can be mixed
to conventional metallic particles of similar composition but of larger size generated
by edge loading (. Fig. 20). Corrosion particles appear greenish/yellowish and globular
in the phagosome/lysosome complex of the macrophages, originally described as
droplet-like cytoplasmic inclusions of wear products of uncertain composition [53]
(. Fig. 21 and b). A more complex mixture of particles appears in the MoM LHTHA
implants, in which wear particles generated at the neck/metallic adapter sleeve interface
by fretting/crevice corrosion can also be present with the addition of titanium from the
stem as aggregates of nano-size of micron-size particles ranging from <1 μm to >500 μm
(. Fig. 22). These large aggregates often show a multilayered structure of greenish/
black/reddish material that can contain blood products positive to PBR [4], [20]. In
implants with non-MoM-bearing surface, the corrosion products are generated at the
neck/stem contact surface in implants with CoCr DMN and at the metallic head/neck
taper surface as large aggregates that break down in the joint cavity into smaller aggregates
phagocytized by the macrophages. Large aggregates of corrosion products lined by giant
cells can also be generated at MoM interfaces of fixation devices, such as metallic plate/
metallic screws (. Fig. 23).
Hemosiderin Particles with Iron Content
Hemosiderin particles containing iron of variable size and quantity can be present in the
periprosthetic soft tissues. The majority of these are derived from degeneration of hemo-